Here is the full list of all 19 MechWarrior 5: Mercenaries achievements.
Destroy 75 assault 'Mechs in a campaign or career. (Counts kills by your entire lance.)
Complete 5 missions with your lance at least 50 tons under max tonnage, in a campaign or career.
Accumulate a net worth of 100,000,000 C-bills in a campaign or career.
Destroy 250 ground vehicles in a campaign or career. (Counts kills by your entire lance.)
Complete 10 Defense missions with the base health at 80% or more, in a campaign or career.
Destroy 75 medium 'Mechs in a campaign or career. (Counts kills by your entire lance.)
Destroy 250 turrets in a campaign or career. (Counts kills by your entire lance.)
Destroy 250 flying vehicles in a campaign or career. (Counts kills by your entire lance.)
Destroy 75 light 'Mechs in a campaign or career. (Counts kills by your entire lance.)
Complete 5 missions while playing co-op, in a campaign or career.
Complete Act 1 of the campaign.
Apply a custom paint pattern or color to one of your 'Mechs in a campaign or career.
Destroy 75 heavy 'Mechs in a campaign or career. (Counts kills by your entire lance.)
Travel to Kooken's Pleasure Pit.
Complete a Raid mission with zero enemy units killed, in a campaign or career.
Have all hardpoints on 4 'Mechs be equipped with tier 4 or higher weapons, in a campaign or career.
Complete 10 Warzone missions, each earning at least 500,000 bonus C-bills, in a campaign or career.
Complete Act 2 of the campaign.
Complete Act 3 of the campaign.